ORNITHOLOGICAL CLUB. 55 



from the interior, I have seen at least two hundred adult males, and 

 they all possessed the bright rufous back, only au occasional individ- 

 ual showing a faint trace of the green. In California, however, where 

 the S. rjifus occurs in its typical condition, that is, with an unmixed 

 rufous back, specimens are not uncommonly found which exhibit a 

 strong approach to the coloration of S. alleni. In these the rufous 

 is seen to be mixed with green in varying proportions. Beyond a 

 certain point they appear never to pass, and all such specimens have 

 the peculiar tail characters of S. rufus as strongly marked as in the 

 most typical examples of the species. We find the same difference 

 between specimens of S. rufus taken in California and on the 

 west coast generally, and those from the interior, that usually ob- 

 tains in species possessed of a similar range, — that is, the coloration 

 is appreciably darker. The locality of specimens, whether from the 

 coast or the interior, may by this means be readily told. 



In Mexico only the S. rvfus appears to occur, and Mr. A. Boucard 

 informed Mr. Ridgway that, having examined hundreds of the Selas- 

 phorus from there, he had never seen an example of the Green- 

 backed form, which, however, he was familiar with from California. 

 One of the strongest proofs of the specific distinctness of the two 

 is seen in the fact that the two birds, in their typical condition, 

 occur at the savie locality and at the same season. Both breed about 

 Nicasio (situated about twenty-five miles north of San Francisco), 

 though Mr. Allen finds the S. alleni very much more abundant than 

 the other. Thus, during the present season (1877), he has shot 

 about forty-five of the former bird, and has only succeeded in taking 

 four of the rufous-backed species. Last year's experience was a 

 similar one. 



This gentleman, whose investigation of these two birds baa 

 extended over several years, and who, it is but proper to state, has 

 always believed them to be distinct, has found a constant difference 

 in size, the ^S*. alleni being the smaller. Such I find to be the case 

 in the several specimens I have measured, and the discrepancy 

 between them is quite considerable when the diminutive size of the 

 birds of this family is taken into account. 



Habits. I am in possession of but few notes bearing upon the 

 habits of this Hummer. Mr. Allen remarks incidentally in a letter 

 that the Green-backs are much the livelier and more active of the 

 two, keeping constantly in the open, and always perching upon the 

 most prominent dead twigs they can find. Their extreme shyness, 



